Wow, this thread almost slipped me by! Better late than never, I guess. Excellent posts by all. There are only a couple of points I can add:

- In Ontario, you can no longer buy a forced-air gas furnace under 90% AFUE. - There are rebates available from the Provincial Government and the Ontario Power Authority (OPA) to upgrade your furnace. A home energy audit is required, (which will cost you ~$350.00), but you could qualify for up to $940.00 in rebates. - Most manufacturers also have rebates available. - If you are truly moving within the next couple of years listen to John:

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AFAIK the big selling feature is "new" furnace, not "fancy" furnace.

Excellent advise. Conversely, if you are staying in the house, the multi-stage gas valves and ECM motors are WELL worth the extra money.

With regard to the quoted "Savings" on fuel costs, it really depends on the age and efficiency of the existing furnace. I have seen consumption cut in half in a number of installs, but it is not common.

Also, since you are moving, don't get talked into spending more on one of the higher end name brands. Even a cheap-o builder furnace will be relatively trouble free for the first 5 years if installed correctly. Please note that I will give the exact opposite advise if you are staying in the house long term.

One other obvious point -- smaller furnaces running longer tend to make for more comfortable houses and lower fuel bills. If you size the furnace to keep your house toasty on the "coldest day in 5 years" that's probably bigger than you need... next time I would go with something sized to "keep the house comfortable on the colder days running most of the time" and put on a sweater or light a fire on the occasional freeze-ups.

Spot on, John. That's why there are multi-stage furnaces that will match their firing rate to what the house needs. Far more efficient heat delivery and comfort than a single stage unit.

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I guess having the furnace burning relatively more of the time would translate into a shorter heat-exchanger life but I've never actually heard that discussed.

Actually, just the opposite. The thermal expansion & contraction from repeated short heating cycles, causes more wear and aging than fewer, longer, heating cycles. Similar to a car with mostly "highway miles" vs "city miles"

Actually, just the opposite. The thermal expansion & contraction from repeated short heating cycles, causes more wear and aging than fewer, longer, heating cycles. Similar to a car with mostly "highway miles" vs "city miles"

Interesting, and very good to know. I guess that pretty much eliminates all of the arguments for "oversizing" a furnace. Thanks !!

Just an update on the new high(er) efficiency('bout 92-93%) furnace I had installed back in the fall....I'm definitely seeing a reduction of 25-30% on my gas bills each month, woo-hoo!....should have done this sooner.

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